Liberal Democrat MP John Hemming has used parliamentary privilege to identify the footballer at the centre of an injunction row as Manchester United midfielder Ryan Giggs.
Newspapers in England have been fighting a gagging order for weeks, which has banned the naming of the sportsman who is alleged to have had a relationship with Big Brother star Imogen Thomas.
But just minutes after the High Court refused to lift the ban, Hemming - who has been campaigning against the use of injunctions and super-injunctions - named Giggs in the House of Commons.
The MP's action finally lifted the blackout on mainstream media identifying the Manchester United star. Mr Hemming said it was not practical to imprison the numerous Twitter users who have already named the player.
"With about 75,000 people having named Ryan Giggs on Twitter it is obviously impracticable to imprison them all and with reports that Giles Coren also faces imprisonment," Hemming said in the House of Commons.
Speaker John Bercow interrupted the Birmingham Yardley MP, telling him that "the occasion for raising the issues of principle involved not seeking to flout for whatever purpose".
Scottish newspaper The Sunday Herald printed a picture of Giggs on their front page a day earlier, with his eyes blacked out with a bar on which "censored" was written.
The newspaper said it was "unsustainable" for newspapers to be banned from printing information that was readily available on the internet.
It said: "We should point out immediately that we are not accusing the footballer concerned of any misdeed. Whether the allegations against him are true or not has no relevance to this debate.
"The issue is one of freedom of information and of a growing argument in favour of more restrictive privacy laws."